Magnetic resonance imaging (MRI) has detected breast lesions that had previously been sub-clinical. However, MRI's 40% false positive detection rate necessitates biopsy of these lesions to confirm diagnosis. No commercially available device exists which allows this procedure to be performed without open biopsy. Several designs for a stereotaxic MRI breast biopsy device have been offered in recent literature however, none provide the l mm needle positioning accuracy required for clinical effectiveness. Our Phase l efforts produced a radio frequency (rf) receiver coil for breast MR imaging with excellent signal-to-noise ratio characteristics and integrated stereotaxic capabilities resulting in submillimeter needle positioning accuracy in phantom studies. This device is a modification of breast coil T803 which has received FDA approval to market and was designed by PI, a Ph.D. biomedical engineer. Phase II support is requested to expand the capabilities of the device to allow biopsy of lesions near the chest wall, to automate the calculation of needle position coordinates and to address clinical issues including breast compression so that l mm needle positioning accuracy can be obtained clinically. Two thousand MR imagers in the U.S. alone indicate commercial application potential for this device. PROPOSED COMMERCIAL APPLICATION: The successful development of a stereotaxic breast biopsy coil will allow physicians to detect and biopsy suspected cancerous lesions with significantly greater sensitivity than current methods allow. Estimated market potential for this device is over $60 million based on 2000 MR imagers in the United States.